This invention relates to electrical conductivity measurements and in particular to an instrument for measuring the deviation of conductivity of a sample from that of a standard. The instrument is especially adapted for use in the soft drink industry for monitoring the syrup to water ratio of the product. The instrument is sometimes referred to as a syrup ratio meter.
The syrup to water ratio of a sample can be determined by measuring the difference in electrical conductivity of the sample and a standard of known syrup to water ratio. In the past, this measurement has been made in a laboratory using laboratory type instrumentation. A sample is brought to the laboratory, the sample and standard are put in separate relatively large conductivity cells, both cells are placed in a water bath to maintain temperature equalibrium, and the conductivity is measured for each cell. The difference in conductivity provides a measure of the difference in syrup to water ratio of the sample and standard. This type of measurement is not satisfactory because the readings are not reliable to better than .+-. a few percent, whereas the soft drink industry requires accuracy and repeatability of measurement in the order of .+-. a few tenths of a percent. At the present time, sugar type drinks are tested by specific gravity measurements and diet type drinks by chemical analysis.
It is an object of the present invention to provide a new and improved instrument and method which is suitable for use at the production line. The instrument should be simple, sensitive, stable and easy to calibrate and use.